Method of making welded connections for sheet metal articles



' A ril 8, 1941.

F G. WAHL 2.237.535

METHOD OF MAKING WELDED CONNECTIONS FOR SHEET METAL ARTICLES Filed Dec.9, 1938 Pig. 8.

INVENTOR. f76d 6. Q) a 7/ Z Patented Apr. 8, 1941 METHOD OF MAKINGWELDED CONNEC- TION S FOR SHEET METAL ARTICLES Frederick G. Wahl,Detroit, Mich, asslgnor of onehalf to Gordon M. Evans, Detroit, Mich.

Application December 9, 1938, Serial No. 244,813

3 Claims.

This invention relates to'the making of articles Irom sheet metal or thelike wherein two or more pieces are joined together at a seam andparticularly where the article thus formed is to be finished with asurface of porcelain or the like.

The invention can be disclosed and described in connection with themaking of relatively deep receptacles, such as for example, the tubportion of a washing machine, although, of course,

the invention is not limited to such an article. It has been thepractice to'- make the tub of a washing machine from a single piece ofmetal subjected to a. drawing operation, and then the shaped article, inmany cases, is given an application of porcelain. There is'aconsiderable draw in the metal in this case and fairly thick sheet stockhas to be employed to stand the draw. Also, the drawing machinery isexpensive and large, with the result that there is a considerable outlayfor equipment.

This invention aims to provide a method wherein an article'such as adeep receptacle can be made from two or more pieces -of sheet metalwithout any substantial drawingjaction. Thus lighter stock can be usedand theinitial capital expenditure for equipment is materially reducedand, moreover, very little sheet metal is wasted in the process. Tothese ends sheet metal parts may be suitably fashioned by a rolling orforming operation or by a stamping operation, or both, and parts to beunited are provided with flanges arranged to abut each other. lflheseflanges are then welded together, but where the flanges meet, a grooveor crack is formed, and

this will not properly take a surface finish of porcelain or the like.To overcome this, the metal of the parts is worked with a spreadingaction to open up the crack or groove and flatten it out, as far as theweld will permit. This minimizes the dimensions of the crack or grooveto, such an extent that a finish of porcelain or the like can besatisfactorily applied.

In the accompanying drawing:

Fig. 1 is a perspective view of a sheet of metal fashioned intocylindrical form with the edges welded together.

. Fig. 2 is a cross sectional view of the cylinder with its endsfashioned properly to constitute Fig. 4 is a further enlarged sectionalview showing the welded seam.

Fig. 5 is a View enlarged to the size of Fig. 3

illustrating a working operation or spreading operation.

Fig. 6 is a view enlarged to the size of Fig. 4 showing the seamstructure after the spreading operation.

Fig. '7 is a diagrammatic view illustrating a finishing operation.

Fig. 8 is anenlarged view showing the surface finish of porcelain or thelike.

Fig. 9 is a view similar to Fig. 5 showing a modified arrangement.

The vessel or tub may be fashioned from a sheet of metal such as steelfashioned into cylindrical form with the edges butt welded'together. Thecylindrical form is shown in Fig. 1, and the cylindrical form I becomesthe side walls of the receptacle. The butt weldat-the edges is suitablytrimmed and finished. Due to the fact that sheet stock is rolled intocylindrical form relatively light gauge stock may be used. Thecylindrical form may next be subjected to a suitable forming operationto fashion the upper edge in the proper manner, as for example, in theform of an inwardly extending roll 2. The opposite end may be fashionedwith an inwardly extending portion or a suitable radius as illustratedat 3, and the extreme end is formed with an outwardly projecting flangeI.

The bottom of the receptacle may be a sheet metal stamping 5 which mayalso be of relatively light gauge stock due to the fact that thestamping is so shallow, and the bottom is provided with a flange 8arranged to abut against the flange 4 as illustrated. The flanges l and6 are properly located relative to each other and are to be weldedtogether. Prior to the complete welding operation, however, the flangesmay be tacked or temporarily connected by spaced'welds.

- The bottom 5 preferably has its outer mne on a radius to somewhatmatch the radius 3 of the body. r

The next step in the making of the receptacle is that of welding theflanges 4 and 6, and this may be done by opposed roller electrodes 1 and8. The receptacle may be revolved on its axis with .the flanges movingbetween the electrodes to form a continuous fiuid tight weld entirelyaround the vessel. This weld is indicated by the overhatch 9 in theenlarged Fig. 4. However, it

' will be noted that quite a substantial groove or crack is left on theinterior of the vessel, as odicated at III. This cannot be properlyfill-tuned it is not a sanitary arrangement in a thing such as a tub'fora washing machine.

Accordinglmthe metal is now worked or spread to minimize the dimensionsof this groove. This may be done after the manner illustrated in Fig.

5. The apparatus used for this purpose is sub- -ject to variationinsofar as this invention is noncerned, but one way of accomplishingthis spreading action is to use a roller 05 disposed to engage the metalon the inside of the seam and a roller l6 arranged to engage the metalon the outside and having a groove H for the reception of the flangeconstituted by the overlapping parts 4 and t.- The flange, however, doesnotseat in the bottom of the'groove H, with the result that the vesseland the rollers are. more or less in a floating position relative toeach other. The rollers l5 and it are urged toward each other withpressure, and a relative rotary motion is caused between the vessel andthe rollers.

shell I and the bottom 5 on opposite sides of the seam is worked andspread apart. This spreading; action will continue until the metalspreads to the point where the weld prevents further spreading. In otherwords, as Fig. 4 is viewed,

the metal portions on opposite sides of the groove are spread outwardlyaway from each other, and more or less flattened. The weld line in Fig.4 is indicated at X; by weld lines we mean the innermost portions of theflanges 4 and 6 which are weld united. The spreading continues and the,weld line is caused to shift toward the sides of the receptacleor themetal stock, at which time the weld connection is drawn taut, so tospeak,

and further spreading stopped. As a result, the 40 inner surfaces of thesheet I and sheet 5 come together in a substantially flush manner withthe weld connection joining the same and lying substantially atthe lineY in Fig. 6.

Now it may well be, and perhaps will be, that 3 the weld line X willvary in its position. In some spots the weld line may be in the positionshow'n in Fig. 4, and in other spots on the same job the weld line maybe further outward ontowards the ends. of the flanges and in still otherspots be further inward toward the groove. Due to the floatingarrangement of the spreading rollers, there is a little greaterspreading action where the weld line is positioned more toward the outeredge of the flange, resulting perhaps these slight variations are notvisible to the eye,

other smoothly with a weld line therebetween. The receptacle may now befinished by finishing the roll at the upper edge or other suitable ordesirable finishing operations and the receptacle is ready to be cleanedor pickled and then given I abase coatof porcelain. This is illustratedin Fig. 7 where the material is sprayed on to the shell by a suitablegun 20. As is well known to those versed in the art, the tub may now bebaked at a suitable'temperature and subsequently a finish coat ofporcelain sprayed-over, the base In this action the metal of both the 25X the radii that the initial groove is formed. The

- coat and then the vessel subjected to another baking operation. Theporcelain-applies evenly over the surfaces and over the smooth weld lineX so that in the finished job no weld on the intefior is appreciablyvisible. In Fig. 8 a more or less diagrammatic illustration is givenshowing the finished job with the porcelain coating 2!. Y

' A variation in the spreading step is illustrated in Fig. 9: Theinterior roller l 5 may be the same as that shown in Fig. :5, butexterior v rollers 22 and 23 are applied to the flange with pressure.Relative rotation between the roller assembly and the vessel' causes themetal to spread to minimize the dimensions of the crack or groove andresult in the structure as shown in Fig. 6.

In the initial fashioning of the flanges on the sheet metal parts, it isdesirable to have a considerable radius at the juncture between thesheet metal body and the flange, as this is good practice in sheet metalworking, as the metal mightbe ruptured or sheared if an attempt be madeto form a sharp bend or break line. It is due to the opposing curvedsurfaces formed on working and spreading of the metal so reduces thedimensions of the groove that a finish of porcelain or the like may besatisfactorily applied, whereas the finish could not be'satisfactorilyapplied with a groove of the initial dimensions. Furthermore, theprovision of initial relatively long radii .at the flanges is desirableas such a formation lends itself to the spreading action, and in factfacilitates the spreadingprocess. I

In the finished article there is, of course, the

\ projecting exterior flange which may, if desired.

be trimmed to reduce its width, but-which may be concealed in anysuitable way, as for example, by the attachment of the legs for the tub,or the projecting flange may be made more or less orna- -mental bymerely disposing a head or rubber or the like over it.

It has been ,found expedient to locate the flanges I and 6 at a cornerof the vessel. In this way, the adjacent metal takesa direction awayfrom the welding rolls I and 8, as shown in Fig. 3, whereby the weldbetween the flanges 4 and 6 may be taken well inwardly of the flangetoward the body 'of the vessel. However, it is within .the invention tolocate the fianges'in parts which are not angularly disposed relative toeach other. Furthermore, by placing the flanges at a corner or the like,especially where there is considerable I radius in the ifitimate job, asshown in Fig. 7, the bulging effect which may be produced by thespreading is more or less absorbed in the curvatur and loses anyvisible'identity. The initial radius given to .the body'of the vessel at3 and-the initial radius adjacent the 'edgesof the bottom may besomewhat less than that of the Eultimate radius. This is shown in an exaerated manner as will be evidenced by comparison of Figs. 2 and 7.' Inthe spreading and bulging operation', the radii may be slightlyincreased and.

the resultant curvature of the adjacent parts of the body and bottom maybe substantially the same. The invention is not limited to a porcelainfinish, but is applicable to .other finishes a crack or groove isundesirable.

lclaimz 1. The method of making a receptacle which comprises fashioninga sheet metal blank into a tubular body having a circumferentiallysmooth where wall at least adjacent one end, forming a flange at saidend of the body with they flange meeting' the tubular wall of the bodyon a curve, fashioning a bottom from sheet metal and forming a flange onthe peripheral edge of the bottom with the flange meeting the metal inthe bottom on a curve, placing the body and the bottom together with theflanges in abutting relationship withthe curved portions defining agroove, welding the interracial surfaces of the flanges together,working the metal of the body and the bottom adjacent the flanges tocause a spreading action substantially until the weld connection isdrawn taut to reduce the dimensions of said groove .to such a size astopresent a surface for the reception of a finish such as porcelain or thelike.

2. The method of making a receptacle which comprises, fashioning a sheetmetal blank into a tubular body having a circumferentially smooth wallat least adjacent one end, forming a circum a curve, placing the bottomand the body together with the flanges in abutting relationship, withthe curve portions defining a groove, welding the interfacial areas ofthe flanges together, working the metal at and adjacent the curvedportions to cause a spreading action until the weld connection issubstantially drawn taut to thereby reduce the dimensions of the grooveto such a size as to present a surface for the reception of a finishsuch as porcelain or the like.

3. The methed of uniting two sheet metal parts in a seam adapted toreceive a finish such as porcelain or the like which comprises, forminga flange on the edge of one sheet metal part with the flange joining thebody of the parton a curve, forming a flange on the other sheet metalpart with the flange joining the body of the part on a curve, placingthe flanges together in abutting relationship, welding the interfacialsurfaces of the flanges together with the curves defining a groove,working the metal in and adjacent the curves to cause a spreading actionsubstantially until the weld connection is drawn taut to thereby' reducethe dimensions of the groove to such a size as to receive the saidfinish.

FRED G. WAHL.

